The present invention relates to a method and a system for replacing a program in a computer, and more particularly to a method and a system for replacing a program running in an uninterruptible online computer system with another program.
In recent days, a remarkable need has risen for uninterruptible online computer systems used, for example, in finance-related or worldwise network systems. To replace a program in such an uninterruptible online computer system, a simple method for temporarily interrupting the computer system can be employed. This method, however, significantly degrades the online service provided by the computer system.
To overcome the shortcoming, a method has been proposed for replacing a program without interrupting an online computer as disclosed in JP-A-1-232432. This proposed method has the ability, however, to replace a current program with a new one only when starting the program. It thus has a disadvantage that the method is not intended for replacing an uninterruptible running program, because there can occur no chance or timing of starting the uninterruptible program intermediately of its online operation. Throughout this specification, a current program means a program currently running on the main storage and a new program means a program to replace the currently-running program.
Moreover, in case two or more different programs are simultaneously run which are closely related, it is necessary to replace these programs with new ones at the same time while they are in operation. However, the proposed method cannot cope with the replacement of two or more programs in operation at the same time. This is another disadvantage of the prior method.
Another method for modifying or replacing a program has been proposed in JP-A-58-4445 or U.S. Pat. No. 4,425,618.
These proposed methods consider no replacement of a program running in an online computer system. They also consider no replacement of two or more programs at the same time while they are in operation.